Discoidin Domain Receptor 1 (DDR1) is a receptor tyrosine kinase, and it is known that DDR1 is activated by collagen as a ligand to transduce signals into cells, and to promote invasion/metastasis or survival of the cells (Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3). DDR1 is considered to be an important factor that links extracellular matrix with malignant transformation of cancer, because high expression and activation of DDR1 is observed in various types of cancers.
For example, it is known that clinically DDR1 is highly expressed in non-small-cell lung cancer, glioma, breast cancer, and the like (Non-Patent Document 4, Non-Patent Document 5, Non-Patent Document 6, and Non-Patent Document 7), and it is reported that high expression correlates with poor prognosis in non-small-cell lung cancer and glioma. Further, in non-small-cell lung cancer and bile duct cancer, enhancement of DDR1 phosphorylation is observed, and its activation is strongly suggested (Non-Patent Document 8, and Non-Patent Document 9).
Studies using RNA interference reveal that DDR1 plays an important role in bone metastasis of lung cancer cells (Non-Patent Document 5), and contributes to tumorigenicity of colon cancer or breast cancer cells as well as their survival in the presence of DNA-damaging agents (Non-Patent Document 10). Accordingly, compounds having a DDR1 inhibitory effect are extremely useful for cancer treatment.
It is also reported that the DDR1 ligand, collagen, is abundantly present in fibrous tissues, and functions mediated through DDR1 activation are involved in various types of fibrosis. For example, DDR1 expression is enhanced in the liver of hepatic cirrhosis patients (Non-Patent Document 11). It is reported that in DDR1 knockout mice, fibrosis in the kidney induced by unilateral ureteral ligation is suppressed (Non-Patent Document 12), and fibrosis in a pulmonary fibrosis model induced by bleomycin is reduced (Non-Patent Document 13). As it is clear from above, DDR1 inhibition is extremely useful for the prevention and treatment of organ fibrosis. DDR1 also enhances lymphocyte migration, and migration and inflammatory functions of macrophages (Non-Patent Document 14, and Non-Patent Document 15). For example, in DDR1 knockout mice, accumulation of macrophages is suppressed in an arteriosclerosis model (Non-Patent Document 15). It is reported that lymphocytes and macrophages also accumulate and are activated in inflammatory diseases such as rheumatoid arthritis, Crohn's disease, ulcerative colitis, and multiple sclerosis. Accordingly, DDR1 inhibition is also extremely useful for the prevention and treatment of these diseases which originate from inflammation.
Examples of DDR1 inhibitory substances include multikinase inhibitors which have DDR1 inhibitory effect as one of their effects. Reported examples include Gleevec which has a 3-pyridylpyrimidine structure and serves as an inhibitor for bcr-abl, c-kit, CSF1R, PDGFRα, and the like (Patent Document 1, Non-Patent Document 16, and Non-Patent Document 17), and Tasigna which has a 3-pyridylpyrimidine structure and serves as an inhibitor for bcr-abl, c-kit, PDGFRα, Lck, Lyn, and the like (Patent Document 2, Non-Patent Document 16, and Non-Patent Document 17). Other reported examples include Sprycel which has a 2-methylpyrimidine structure and serves as an inhibitor for the Src family and the like (Patent Document 3, Non-Patent Document 16, and Non-Patent Document 17), INNO-406 which has a bipyrimidin-2-ylamino structure and serves as an inhibitor for bcr-abl, PDGFRα, Lyn, ZAK, and the like (Patent Document 4, and Non-Patent Document 18), and LCB03-0110 which has a thieno[3,2-b]pyridine structure and serves as an inhibitor for the Src family and the like (Non-Patent Document 19).
However, compounds that selectively inhibit DDR1 are not yet known.